available for shore birds and it 

 helped control mosquitoes by 

 enhancing standing water evapora- 

 tion. Ditches were partially 

 blocked so water was retained 

 but did not flow out over the 

 marsh surface. Bird use was 

 reported to immediately increase 

 without any loss in mosquito 

 control . 



Some of these techniques form 

 part of "open marsh water management" 

 (OMWM), an alternative to parallel 

 ditching and insecticides for mosquito 

 control that has been developed by the 

 New Jersey Department of Environmental 

 Management (Ferrigno and Jobbins 1968; 

 Ferrigno et al. 1975). Using this 

 approach involves selective ditching 

 of major mosquito breeding depres- 

 sions, filling shallow depressions 

 on the marsh surface, and care- 

 fully constructing some ditches to 

 collect water in ponds that are deep 

 enough at all times to contain small 



fish which feed on mosquito larvae. 

 Studies have been carried out to 

 document the effectiveness of OKWM in 

 controlling mosquitoes and in 

 enhancing the wildlife value of the 

 marsh (Ferrigno 1979; Ferrigno 

 et al. 1975). This contrasts with 

 traditional parallel or grid ditch- 

 ing--a practice that has been of 

 questionable value in controlling 

 mosquitoes and that is thought to have 

 had varying (and often undesirable) 

 impacts on overall marsh ecology 

 (Daiber 1974). 



POLLUTION 



Because the high marshes are 

 above mean high tide, most of the time 

 they are exposed to the atmosphere 

 rather than to tidal waters (Figure 

 25). As a result, deposition of 

 particulate matter from the air or in 

 precipitation can be major pathways 

 for pollutant inputs. Ketals, toxic 



E 



_l 



in 



> 



< 

 > 



UJ 



_l 

 UJ 



1.0 

 2.0 - 



LO 



0.0 - 



-1.0 - 

 -2.0 - 



AVERAGE FRACTION OF TIME IMMERSED 

 0.8 0.6 0.4 0.2 



Figure 25. Amount of time the grasses and surface sediments at Farm Creek, 

 Connecticut, are exposed to the atmosphere at different elevations across the 

 marsh (McCaffrey 1977). 



54 



